The injection of alloys in the semisolid state, is highly effective in reducing casting porosity, particularly the one due to turbulences during die filling. On the other hand, the use of semisolid billet poses additional difficulties about either proper alloy re-heating and die design, especially runner and gate system. Obviously gates must be thicker than in traditional diecasting, because of the higher alloy viscosity, however no standards for a good die design are today available in the literature and each manufacturer refers to his own experience and know-how. The aim of this work is to evaluate the effect of the various runner and gate geometrical parameters on the filling pattern, taking also into account the influence of different solid fractions, not only those related to not properly controlled re-heating temperature, but also those typical of rheocasting technology. The study was carried out by means of a numerical simulation commercial software (Procast), considering a typical aluminun-silicon alloy (A356), whose thermo-fluid dynamics properties needed for simulation are mostly available. The results obtained will be subsequently used for the fabrication of an experimental die, for the production of dumb bell and toughness specimens, for future tests in the University diecasting laboratory.
Analysis of semi-solid diecasting runner-gate system as a function of solid fraction
BERTOLI, Ermanno;FURLONI, Disman;POLA, Annalisa;ROBERTI, Roberto
2005-01-01
Abstract
The injection of alloys in the semisolid state, is highly effective in reducing casting porosity, particularly the one due to turbulences during die filling. On the other hand, the use of semisolid billet poses additional difficulties about either proper alloy re-heating and die design, especially runner and gate system. Obviously gates must be thicker than in traditional diecasting, because of the higher alloy viscosity, however no standards for a good die design are today available in the literature and each manufacturer refers to his own experience and know-how. The aim of this work is to evaluate the effect of the various runner and gate geometrical parameters on the filling pattern, taking also into account the influence of different solid fractions, not only those related to not properly controlled re-heating temperature, but also those typical of rheocasting technology. The study was carried out by means of a numerical simulation commercial software (Procast), considering a typical aluminun-silicon alloy (A356), whose thermo-fluid dynamics properties needed for simulation are mostly available. The results obtained will be subsequently used for the fabrication of an experimental die, for the production of dumb bell and toughness specimens, for future tests in the University diecasting laboratory.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
